BTP officers are today releasing CCTV images following a robbery and an attempted robbery on the London Underground.
The first incident happened at Colindale station at 5pm on Sunday 23 June.
A man is reported to have approached the victim near the ticket gates and pulled a gold chain from her neck before leaving the scene.
The second incident happened at Manor House station at 10.55am on Friday 28 June.
A man is reported to have approached two people and attempted to take their property.
When they resisted the suspect pulled a knife and threatened the victims.
It followed an incident at a bus stop outside the station where a man threatened bus passengers with a knife.
Officers believe the incidents may be linked. They wish to speak to the man in the images who may have further information.
Anyone who recognises him is asked to contact BTP by texting 61016 or by calling 0800 40 50 40 and quoting reference 36 of 24/06/19.
